1. Field of the Invention
The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and apparatus for improving fast mobility Internet Protocol version 6 (FMIPv6) with a link identifier prefix (LinkID prefix) in a portable Internet system according to the Institute of Electrical and Electronics Engineers (IEEE) 802.16d/e, wireless broadband Internet (WiBro), and World Interoperability for Microwave Access (WiMAX), among others.
2. Description of Related Art
A fourth generation mobile communication unifies systems, such as IEEE 802.16d/e, WiBro, and WiMax, among others. In the fourth generation mobile communication, satellite networks, wireless networks, digital broadcasting networks, and video broadcasting networks are unified into a single network and systematically interoperate with each other. Accordingly, a user may utilize a communication service such as a portable Internet in a preferred state, with any network.
FIG. 1 is a diagram illustrating a conventional wireless communication system 100 environment. Referring to FIG. 1, mobile nodes (MN) may receive a communication service, such as a call, digital broadcasting, and downloading or uploading of digital medial data, among others, via access points (APs). The APs and an access router (AR) are connected to each other, based on an Ethernet. A routed Internet Protocol (IP) via a control of the AR is sent or received to/from a destination node or a destination server via a corresponding AP.
In FIG. 1, the AP functions as a bridge for a fast connection to the MN. Also, the AP functions to process scheduling of wireless resources and a radio frequency (RF) control function. The AR is an IP terminating point which is mainly in charge of a Layer 3 (L3), and routes IP packets so that the IP packets may be appropriately sent and received between the APs and the MNs. The AR interoperates with a home agent (HA) which performs a mobile IP registration allocation and a data encapsulation. The HA is connected to the AR via an IP core network including an IP public access network. In addition, an Authentication/Authority/Accounting (AAA) server, a quality manager, a location register, and an application server, among others, may be connected to the AR via the IP core network.
In the conventional wireless communication system 100 environment, the AR may support mobility of nodes according to FMIPv6 which is advanced IPv6. Fast handoff by FMIPv6 is disclosed in RFC4068. To support an IP as described above, the AR manages a candidate access router (CAR) table as shown in FIG. 2.
When a MN moves from a service area of a first AP (AP1) of a subnet where a first AR (AR1) covers, to a service area of a second AP (AP2) of a subnet where a second AR (AR2) covers, in an environment as shown in FIG. 1, an access point Media Access Control (AP MAC) address or a Basic Service Set Identifier (BSSID) may be acquired by scanning an L2 beacon. Accordingly, the MN inserts the BSSID into a Proxy Router Solicitation (PRS) message, and sends the message to a previous AR. For example, the message may be sent to the AR1 illustrated in FIG. 2, to acquire information about a new AR, for example, the AR2 shown in FIG. 2.
The previous AR, for example, the AR1, inserts information, for example, PREFIX 2 of FIG. 2, about the new AR, for example, the AR2, into the PRS message and thereby generates an advertisement. Accordingly, the MN constructs a new care-of address (NCoA), and sends a predetermined binding message to the previous AR which is the AR1. According to an exemplary implementation, the binding message consists of the NCoA and the BSSID. The MN receives a predetermined acknowledgement (Ack) message from the previous AR, for example, the AR1, according to the binding message. The previous AR, for example, the AR1, transfers IP packets of an L3 to the new AR, for example, the AR2.
Therefore, when the MN moves to the subnet of the AR2 and sends a predetermined advertisement message to communicate with the AP2, the new AR (AR2) receives the advertisement message from the previous AR (AR1) and sends buffered IP packets to the MN. As described above, when performing a handoff from the subnet of the AR1 to the subnet of the AR2, a significant amount of signaling occurs among MNs, APs, and ARs.
In a conventional handoff method, an L3 handoff, such as a subnet change, may not be directly determined from information which is contained in an L2 beacon. Accordingly, when the AP1 and the AP2 belong to an identical subnet which is connected to an identical AR, the L3 handoff is also performed in the conventional handoff method. Accordingly, unnecessary signaling still occurs between the MN and the AP1, between the MN and the AR1, and between the AR1 and the AR2. Also, in the conventional handoff method, there is a disadvantage of overhead that prefixes corresponding to the APs and the ARs must be preset in the candidate access router (CAR) table, as shown in FIG. 2, to support a handoff.
Accordingly, there is a need for an improved system and method for performing a handoff by dynamically constructing an access router table ARs according to a link identifier prefix that a MN receives from any of the ARs, and thereby detecting an appropriate AP.